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Thread: Honeywell DU 145 Setting

  1. #1
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    Default Honeywell DU 145 Setting

    I would be grateful if someone who understands these things could help with a question about the setting for a Honeywell DU145 ABV.

    The pump details are Grundfos UPM3 15-75 with a water flow of 15.2l/min/910l/h at T20C with a permissible resistance of 25kPa/250mbar. The pump max has been set on high as I have 19 radiators.

    The boiler sits 4 feet below the landing; the 22mm plastic piping is 31ft from boiler to ABV. TDH = 1.46 Metres( my calculation?)

    I ask because I am getting some gurgling from one radiator on first opening (even with other valves already open). The ABV is currently set on 2.5 but even with radiators open, there is some bypass in operation.

    I appreciate that there is a 'hands on' way of setting the ABV but it would be nice to know what the theoretical ABV setting should be.

    Thanks.

  2. #2
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    Isn't the boiler minimum flow rate an important factor to consider too? I too get bypass in operation when the radiators are open, if I close the by-pass any more then the boiler complains about the low flow rate.

  3. #3
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    Thanks. I have worked it a number of ways, and I get a theoretical result of 2.5 ish. I had the whole CH system on last night to get some air out of one of the vertical pipes, and the boiler seemed quite happy as I went around the house turning off individual zones.

    My installer thought he had left it set at 3 but as I found out when I came to adjust it, the calibration ring had not been installed properly in the cap. The moral is that if you have a helper: then never assume, check.

  4. #4
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    2.5 what ?

    2.5 metres of head ? Or do you mean 0.25 bars ?

  5. #5
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    Sorry - I was referring to the settings on the valve which don't have the decimal point: 0.25 bars.

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